Math Trick: How to multiply large numbers in your head?

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[brainbulb]

NOTE: The math trick works also for others case (see the replies to the comments below), but it is not worth it, since the purpose of the trick is to make things easier, so for large numbers is meant numbers close to 100. What is the point of using this method e.g. 64x58, in which case when we subtract from 100 we get very large numbers (we get into a loop of multiplying large numbers), leading to no simplification.

[kayleewilkinson]

Awesome trick! I love having new ways to look at multiplying larger numbers its something that can be hard to keep track of in my head! Thanks!

[eleonorecarrez]

Can you show me this method with 52x52?

[myronochea]

what if you're bad ad subtractions too and can't subtract with numbers 10 and up?